[Affected versions]:

• Fx69.0b8
• Fx68.0.1 RC
• Fx70.0a1

[Affected platforms]:

• win 10 ARM

[Steps to reproduce]:

1. Go to this link and download the 'Table images' folder.
2. Launch Firefox.
3. Open the 'table image.html' file in Firefox.
4. Perform a zoom-in and zoom-out operation multiple times from the touch screen.

[Expected result]:

• All operations are done smoothly without any issues.

[Actual result]:

• Either the zoom-in or zoom-out operation gets stuck, never at the same %.

[Regression range]:

• This occurs on the earliest aarch x64 build so it's not a regression.

[Additional notes]:

• This issue does not occur on Chrome.
• On other images or web-pages this issue does not occur (the zoom-in/zoom-out operations are done smoothly every time the user performs it).
• Let me know if a video of the issue would be more helpful and I'll try to capture it.
• I've also encountered the same issue while trying to zoom-in/zoom-out multiple times on this image.

Zoom gestures on Windows touchscreen currently perform reflowing-zoom. Reflowing-zoom issues are tracked in the Layout component.

The priority flag is not set for this bug.
:jwatt, could you have a look please?

For more information, please visit auto_nag documentation.

I'm going to defer to botond.

Based on the symptoms and briefly playing around with the page in a Windows touchscreen, this sounds like an imperfection in how pinch gestures are mapped onto full-zoom events.

I don't think it's worth spending time on tweaking this. The proper solution is to have pinch-zoom gestures perform scaling-only (non-reflowing) zoom, tracked in bug 789906.